Irmtrud E. Jonas

Dental Age in Southwest Germany A Radiographic Study

Abstract: A cross-sectional study was undertaken in order to assess the dental age of healthy Southwest German boys and girls between the ages of 2 and 20 years by evaluating 1,003 panoramic radiographs. Dental age was assessed according to the method of Demirjian et al. All permanent teeth of the lower left jaw except the third molar were rated, the development of each tooth was divided into 8 defined stages.Statistical evaluation revealed a correlation betweeen the parameters chronological age and score sum of r = 0.85 for girls and r = 0.89 for boys. The values of the score sum in relation to chronological age were distributed as in a logistic function. Two gender-specific equations for calculating dental age were devised and a marked sexual dimorphism was found. With the beginning of root formation, the girls showed accelererated development.The fact that dental age distribution in Southwest Germany is not significantly correlated to that of a French-Canadian collective underlines Demirjians demand for regional standards of dental development to be calculated using his score system.Zusammenfassung: Anhand der Panoramaschichtaufnahmen von 1003 gesunden Jungen und Mädchen im Alter von zwei bis 20 Jahren, vorwiegend aus der kieferorthopädischen Abteilung der Universitätsklinik für Zahn-, Mund- und Kieferheilkunde, Freiburg i. Br., wurden in einer Querschnittsuntersuchung Zahnalterstabellen erstellt. Zur Anwendung kam das Auswertungsverfahren nach Demirjian et al. Alle bleibenden Zähne des linken Unterkieferquadranten mit Ausnahme des Weisheitszahnes wurden nach acht Mineralisationsstadien beurteilt.Die mathematisch-statistische Auswertung der Daten und ihre Signifikanzprüfung ergaben eine Korrelation des Parameters Scoresumme mit dem chronologischen Alter von r = 0.85 für Mädchen und r = 0,89 für Jungen. Die Wertepaare Scoresumme zu chronologischem Alter kamen in ihrer Verteilung einer logistischen Funktion nahe. Es wurden geschlechtsspezifische Gleichungen zur dentalen Altersbestimmung aufgestellt und deutliche geschlechtsspezifische Unterschiede gefunden. Mit Einsetzen der Wurzelbildung trat eine Akzeleration bei den Mädchen auf.Die nicht signifikante Korrelation der dentalen Altersverteilung im südwestdeutschen Raum mit einer frankokanadischen Vergleichsgruppe untersteicht Demirjians Forderung nach regionalen Zahnalterstabellen.

A surface EMG electrode for the simultaneous observation of multiple facial muscles.

With previous surface electromyography (sEMG) electrodes it has been difficult to combine small outer dimensions and secure skin attachment. We resolved this problem by developing a new skin attachment technique that yields firm electrode fixation without requiring an acrylic housing. Consequently, we could reduce the outer electrode dimensions to 4-mm diameter and only 1.5-mm thickness. In a bipolar montage, this electrode allows an inter-electrode distance of 8 mm. This improves measurement selectivity and, because of the small dimensions, makes possible the non-invasive observation of multiple facial muscles with a minimum of obstruction. Our new technique was tested on a group of 11 professional trumpeters. They were instructed to perform a series of muscle-specific facial poses and to play exercises on their instruments while EMG signals were recorded simultaneously from seven different perioral muscles. Although the skin attachment was subjected to high stress during trumpet playing, more than 98% of electrode placements yielded a secure mechanical and electrical connection. Muscle selectivity of the signals recorded during the facial poses was similar to that obtained in a previous investigation using intra-muscular fine-wire electrodes. Crosstalk in the perioral area was estimated to be lower than 25%. The availability of an unobstructive sEMG electrode for simultaneously observing multiple facial muscles opens up a wide range of applications (e.g. in speech research, psychophysiology and orthodontics).

A randomized prospective long‐term study of two oral appliances for sleep apnoea treatment

Various types of mandibular protrusive appliances have revealed different treatment success in mild‐to‐moderate obstructive sleep apnoea (OSA). The present study compared the long‐term effect of two different appliances in the treatment of OSA. A total of 103 patients with OSA were randomized and treated with an IST® or Thornton Anterior Positioner (TAP™) appliance. They were followed‐up after a short‐term treatment period of 6 months and long‐term treatment period of over 24 months. Sleep studies in the sleep laboratory were conducted with and without the appliances, and various questionnaires assessing subjective daytime sleepiness, sleep quality, quality of life and symptom scores were administered at each time interval. Quality of life, sleep quality, sleepiness, symptoms and sleep outcome showed significant improvement in the short‐term evaluation with both appliances, but the TAP™ appliance revealed a significantly greater effect. After more than 2 years of treatment, sleep outcomes revealed an equal effect with both appliances. The subjective benefits achieved initially lessened significantly. This study illustrates that both the IST® and the TAP™ appliances are effective therapeutic devices for OSA after a period of over 24 months. Lack of compliance may be due to insufficient improvement in anticipated subjective symptoms and/or a recurrence of symptoms over time.

Dental Anomalies as a Microsymptom of Palatal Canine Displacement

Abstract.Aim: A retrospective study was performed to investigate whether palatal canine displacement is associated with other dental features permitting early clinical diagnosis of the eruption disturbance. Patients and Methods: The study was based on the complete records of 235/8556 patients at the Department of Orthodontics, School of Dental Medicine, University of Freiburg i.Br. (mean age = 14.11 years) with at least one palatally displaced permanent canine. These patients were examined for ten different morphologic parameters, e.g. impaction and congenital absence of further teeth, hypoplastic, peg-shaped, rotated and congenitally missing upper lateral incisors, supernumerary teeth, Angle classification, and cover-bite (= “Deckbiss”). The data were compared with those of a control sample of the same size with physiologic upper canine eruption (mean-age = 10.0 years). Furthermore, in a right/left comparison the local influence of anomalies of the upper lateral incisors on palatal canine displacement was evaluated by multiple linear regression analysis. Results: The statistical analyses revealed that the risk of palatal canine displacement was significantly higher in patients with hypoplasia, peg shape or congenital aplasia of upper lateral incisors, further impacted and congenitally missing teeth and cover-bite. The intergroup differences in terms of gender, rotation of upper lateral incisors and Angle classification were not statistically significant. The right/left comparison revealed a significantly higher risk of palatal canine displacement in association with an adjacent hypoplastic or peg-shaped lateral incisor and with aplasia of the contralateral upper incisor. Conclusion: The clinical significance of the study is that the occurrence of palatally displaced canines is often closely linked with other dental anomalies. In this context, anomalies of upper lateral incisors, aplasia or impaction of further teeth, and the anomaly of cover-bite may serve as indicators of palatal canine displacement. A retarded development of the upper lateral incisor seems to be more disturbing for physiologic canine eruption than aplasia. In patients exhibiting the stated microsymptoms, close clinical follow-up of the maxillary permanent canine eruption during the late exfoliation period is strongly recommended.Zusammenfassung.Ziel: In einer retrospektiven Studie wurde untersucht, ob die palatinale Eckzahnverlagerung mit anderen dentalen Anomalien assoziiert ist, die klinisch eine frühzeitige Diagnose der Durchbruchsstörung ermöglichen. Patienten und Methoden: Die Auswertung erfolgte anhand der Behandlungsunterlagen von 235/8556 Patienten der Poliklinik für Kieferorthopädie der Klinik für Zahn-, Mund- und Kieferheilkunde des Universitätsklinikums Freiburg i.Br. (mittleres Alter = 14,11 Jahre), die wenigstens einen palatinal verlagerten Eckzahn aufwiesen. Diese wurden auf zehn verschiedene morphologische Parameter hin untersucht, wie z.B. die Verlagerung und Nichtanlage weiterer Zähne, Hypoplasie, Zapfenform, Rotation und Nichtanlage oberer seitlicher Schneidezähne, überzählige Zahnanlagen, Angle-Klassifikation und Deckbiss, und die Ergebnisse mit einer gleich großen Kontrollgruppe ohne Eckzahnverlagerung (mittleres Alter = 10,0 Jahre) verglichen. Zusätzlich erfolgte mittels multipler linearer Regression in einem Seitenvergleich die Analyse des lokalen Einflusses veränderter oberer lateraler Inzisivi auf die palatinale Eckzahnverlagerung. Ergebnisse: Die statistische Auswertung ergab, dass das Risiko zur Eckzahnverlagerung für Patienten mit Hypoplasie, Zapfenform oder Nichtanlage oberer seitlicher Schneidezähne, mit Verlagerung oder Nichtanlage weiterer Zähne sowie mit Deckbiss signifikant erhöht war. Die Gruppendifferenzen bezüglich des Geschlechts, der Rotation oberer I2 und der Angle-Klassifikation waren statistisch nicht auffällig. Im Seitenvergleich war das Risiko zur palatinalen Eckzahnverlagerung bei Auftreten von Hypoplasie oder Zapfenform des benachbarten seitlichen Schneidezahnes bzw. bei Nichtanlage des kontralateralen I2 signifikant erhöht. Schlussfolgerung: Für die Klinik zeichnet sich ab, dass das Auftreten palatinal verlagerter Canini häufig mit anderen dentalen Anomalien verbunden ist. Zu beachten sind in diesem Zusammenhang v.a. Veränderungen oberer seitlicher Schneidezähne, Nichtanlage oder Verlagerung weiterer Zähne und der Deckbiss als Indikatoren für eine mögliche palatinale Verlagerung des Eckzahnes. Eine verzögerte Entwicklung des oberen seitlichen Schneidezahnes scheint dabei den normalen Eckzahndurchbruch mehr zu stören als seine Nichtanlage. Bei Vorliegen der genannten Mikrosymptome ist daher in der späten Phase des Wechselgebisses klinisch eine intensive Kontrolle des Eckzahndurchbruches im Oberkiefer anzuraten.

In vitro investigation into the biological assessment of orthodontic wires.

The alloys used in orthodontics are subject in the moist environment of the oral cavity to various corrosion processes. If the products of the corrosion are introduced into a biological system they may cause changes. In the present investigation the corrosion rate of 23 different orthodontic wires (preformed archwires and straight wires) made from 5 different alloys were examined in a nutrient medium by ICP-AES analysis, and the influence of the corrosion products on the cytotoxicity of a fibroblast culture was investigated using Mosmanns MTT test. The nickel-titanium wires Nitinol®, Sentalloy® and Original Chinese Wire® and the β-titanium alloy TMA® had no effect on the rate of cell proliferation. Nor did stainless steel wires inhibit growth significantly, with the exception of Australian Wire® and Wildcat Wire®. The manganese-steel alloys Noninium® h and Mezanium® caused significant reductions in growth rate, which were attributed to the manganese ions released by the corrosion. The most severe growth inhibition was caused by the Co−Cr−Ni alloy Elgiloy®, and this reaction is independent of the 4 levels of resilience. The degree of growth inhibition depended upon the concentration of corrosive cobalt and nickel ions in the eluate. In spite of the differences observed, all the orthodontic wires examined are graded under ISO-standard 10993-5 as “non-cytotoxic”. The degree of toxicity was found to be determined essentially by the corrosion rate of the alloy and the cytotoxic characteristics of the resulting trace elements.ZusammenfassungDie in der Kieferorthopädie eingesetzten Legierungen unterliegen im feuchten Milieu der Mundhöhle korrosiven Prozessen. Werden diese Korrosionsprodukte in ein biologisches System eingebracht, können diese Veränderungen hervorrufen. In der vorliegenden Studie wurde die Korrosionsrate von 23 verschiedenen kieferorthopädischen Drahtbögen und Drähten aus fünf unterschiedlichen Legierungstypen im Nährmedium mittels der ICP-AES-Analyse untersucht und der Einfluß der Korrosionsprodukte auf die Zytotoxizität einer Fibroblastenkultur mit dem MTT-Test nach Mosmann analysiert. Die verwendeten NiTi-Drähte (Nitinol®, Sentalloy® und Orginal Chinese Wire®) sowie die β-Titanium-Legierungen (TMA®) beeinflußten die Zellproliferationsrate nicht. Ebenso zeigten die Edelstähle bis auf die Ausnahmen Australian Wire® und Wildcat Wire® keine signifikanten Wachstumshemmungen. Die Mn-Stähle Noninium® h und Menzanium® bewirkten signifikante Wachstumshemmungen, die auf die korrosiv gelösten Manganionen zurückzuführen waren. Die stärkste Wachstumshemmung wurde durch die CoCrNi-Legierung Elgiloy® hervorgerufen, wobei die Reaktion unabhängig von den vier verschiedenen Härtegraden war. Das Ausmaß der Wachstumshemmung stand in Beziehung zu der Konzentration an korrosiv gelösten Kobalt- und Nickelionen in den Eluaten. Trotz der beobachteten Unterschiede sind jedoch alle geprüften kieferorthopädischen Drähte gemäß der ISO-Norm 10993-5 als nicht zytotoxisch einzustufen. Es zeigte sich, daß der Grad der Zytotoxizität im wesentlichen durch die Korrosionsrate der Legierungen und von den zytotoxischen Eigenschaften der korrosiv gelösten Spurenelemente bestimmt wird.

One- or Two-Stage Palate Closure in Patients With Unilateral Cleft Lip and Palate: Comparing Cephalometric and Occlusal Outcomes

Objective: To assess facial growth and dentoalveolar development in two groups of patients with complete unilateral cleft lip and palate. Primary surgical treatment differed in the timing of hard palate closure. Design: Forty-three patients with unilateral cleft lip and palate were examined. Twenty-two patients underwent early one-stage closure of the hard and soft palate cleft (mean age 23.0 ± 4.7 months); in 21 patients, the hard palate closure was delayed to 86.3 ± 39.2 months of age. Lateral cephalograms and dental casts were consecutively analyzed at four stages between 6 and 18 years of age. Results: Lateral cephalometric analysis revealed no significant intergroup differences in the sagittal and vertical craniofacial dimensions at any time. Dental cast analysis showed constriction of the upper anterior arch width at the ages of 6 and 10 years in patients with one-stage surgical palate closure, but a difference could no longer be verified at the ages of 15 and 18 years. Conclusions: The transverse distances in the upper jaw developed initially more positively in the group with delayed hard palate closure, but it became apparent later that the transverse deficiency after one-stage palate closure could be compensated for. When considering surgical treatment in general, the advantages of the delayed hard palate closure must be weighed against criteria favoring the early one-stage closure of the hard and soft palate.

Smart Bracket for Multi-dimensional Force and Moment Measurement

Atraumatic, well-directed, and efficient tooth movement is interrelated with the therapeutic application of adequately dimensioned forces and moments in all three dimensions. The lack of appropriate monitoring tools inspired the development of an orthodontic bracket with an integrated microelectronic chip equipped with multiple piezoresistive stress sensors. Such a ‘smart bracket’ was constructed (scale of 2.5:1) and calibrated. To evaluate how accurately the integrated sensor system allowed for the quantitative determination of three-dimensional force-moment systems externally applied to the bracket, we exerted 396 different force-moment combinations with dimensions within usual therapeutic ranges (± 1.5 N and ± 15 Nmm). Comparison between the externally applied force-moment components and those reconstructed on the basis of the stress sensor signals revealed very good agreement, with standard deviations in the differences of 0.037 N and 0.985 Nmm, respectively. We conclude that our methodological approach is generally suitable for monitoring the relatively low forces and moments exerted on individual teeth with fixed orthodontic appliances.

sleep-related Obstructive Disordered Breathing in Cleft Palate Patients after Palatoplasty

&NA; Sleep‐disordered breathing is frequently associated with children presenting congenital midface defects. Because of structural and functional anomalies in the upper airway, children with cleft palate, especially after surgery, may carry a higher risk of developing sleep‐disordered breathing. However, the presence of such sleep‐disordered breathing in older cleft palate children has not been emphasized. The aim of this comparative overnight cardiorespiratory sleep study was to evaluate cleft palate patients according to sleep‐disordered breathing. A group of 43 cleft palate children (17 girls and 26 boys; mean age, 12.1 ± 3.8 years) was compared with a control group of 20 randomly selected, noncleft children matched for age, sex, and body mass index. None of the patients suffered from manifest sleep‐disordered breathing. Cleft palate patients had a statistically significantly higher respiratory disturbance index and snoring index, but no increased apnea index. The data suggest that cleft palate patients having undergone primary closure of the palate demonstrate microsymptoms of nocturnal upper airway obstruction. (Plast. Reconstr. Surg. 110: 392, 2002.)

Contribution to the Biological Assessment of Orthodontic Acrylic Materials Measurement of their Residual Monomer Output and Cytotoxicity

Abstract: The acrylic materials used in orthodontics for the fabrication of removeable appliances are subjected in the oral cavity to processes of change which influence their physical, mechanical and biological properties. It is therefore essential that every newly developed material must be judged in terms of its clinical value.In the present study, 2 orthodontic cold-cure acrylics, Orthocryl® and Forestacryl®, and 4 orthodontic photocure acrylics, Triad®, Wil-O-Dont®, Odontolux® and Lux-A-Tech®, were investigated and compared with 2 prosthetic acrylic materials, the cold-cure acrylic Palapress® and the hot-cure acrylic Paladon®. The quantity of residual monomers from methyl methacrylate (MAA) or urethane dimethacrylate (UDMA) eluted from the sample in a given time after the processing was estimated by high pressure liquid chromatography (HPLC). The cytotoxic properties of the materials were examined by Mosmanns proliferation-inhibition test with an established culture of fibroblasts (=MTT test).The hot-cure acrylic Paladon® produced by far the smallest amount of eluted residual monomer and the least growth inhibition in the MTT test. The prosthetic cold-cure acrylic Palapress® achieved significantly better results than the orthodontic cold-cure materials Orthocryl® and Forestacryl®. The photocure acrylics released less UDMA than did the cold-cure acrylics MMA. In the cell culture test, all the orthodontic materials examined were assessed as “slightly cytotoxic”; the prosthetic acrylics were graded under ISO-standard 10993-5 ans“non cytotoxic”. After soaking the plastic material in water for 3 days its cytotoxic properties, as exemplified by the cold-cure acrylic Forestacryl® and the photocure acrylic Triad®, were reduced, and during the following investigation no more inhibition of growth was observed. It was possible to confirm with the test used that, for Triad®, it is necessary to carefully remove the oxygen- inhibition layer of the photocure acrylic in order to improve the biological properties.The influence of the plastic material on fibroblast cultures was assessed, among other methods, by the quantity of residual monomers liberated. These were significantly reduced after soaking the manufactured substance in water for 3 days. Careful laboratory treatment of the photocure acrylics is necessary in order to improve their biological properties.Zusammenfassung: Die in der Kieferorthopädie bei der Herstellung herausnehmbarer Geräte verwendeten Kunststoffe unterliegen in der Mundhöhle Veränderungsprozessen, die ihre physikalisch-mechanischen und biologischen Eigenschaften mitbestimmen. Neu entwickelte Werkstoffe müssen sich an den klinisch bewährten Materialien messen lassen.In der vorliegenden Studie wurden zwei kieferorthopädische Kaltpolymerisate Orthocryl® und Forestacryl® sowie vier kieferorthopädische Lichtpolymerisate Triad®, Wil-O-Dont®, Odontolux® und Lux-A-Tech® vergleichend zu zwei prothetischen Kunststoffen, dem Kaltpolymerisat Palapress® und dem Heißpolymerisat Paladon®, untersucht. Mit der Reversed-Phase-Hochdruckflüssigkeitschromatographie (HPLC) wurde die Menge des von einem Probekörper nach der Verarbeitung in Wasser eluierten Methylmethacrylat-(MAA-) bzw. Urethandimethacrylat-(UDMA-)Restmonomers im zeitlichen Verlauf bestimmt. Die zytotoxischen Eigenschaften der Werkstoffe wurden im Proliferationshemmtestverfahren nach Mosmann an einer etablierten Fibroblastenkultur untersucht (=MTT-Test).Das Heißpolymerisat Paladon® zeigte mit Abstand die geringsten Mengen an eluiertem Restmonomer und die geringste Wachstumshemmung im MTT-Test. Das prothetische Kaltpolymerisat Palapress® erreichte wesentlich bessere Ergebnisse als die kieferorthopädischen Kaltpolymerisate Orthocryl® und Forstacryl®; die Photopolymerisate setzen weniger UDMA frei als die Kaltpolymerisate MMA. In der Zellkulturprüfung wurden alle untersuchten kieferorthopädischen Kunststoffe als “gering zytotoxisch” bewertet; die prothetischen Kunststoffe wurden als “nicht zytotoxisch” gemäß der ISO-Norm 10993-5 eingestuft. Nach Lagerung der Kunststoffe für drei Tage in Wasser konnten die zytotoxischen Eigenschaften am Beispiel des Kaltpolymerisats Forestacryl® und des Photopolymerisats Triad® verbessert werden; die Kunststoffe übten in den Folgeuntersuchungen keine Wachstumshemmung mehr aus. Für Triad® konnte mit den verwendeten Tests die Notwendigkeit einer sorgfältigen Entfernung der Sauerstoffinhibitionsschicht bei den Lichtpolymerisaten zur Verbesserung der biologischen Eigenschaften bestätigt werden.Der Einfluss der Kunststoffe auf Fibroblastenkulturen wird unter anderem durch die Menge an freigesetzten Restmonomeren bestimmt, deren Quantität konnte duch eine dreitägige Lagerung der hergestellten Kunststoffe in Wasser deutlich reduziert werden. Eine sorgfältige labortechnische Verarbeitung der Lichtpolymerisate ist zur Verbesserung der biologischen Eigenschaften notwendig.

Occlusal Side Effects Caused by a Mandibular Advancement Appliance in Patients with Obstructive Sleep Apnea

Mandibular advancement appliances (MAA) have been established as an alternative treatment option for obstructive sleep apnea (OSA). Although the therapeutic effect of these devices has been proven both clinically and polysomnographically through various studies, there are very few follow-up examinations in existence concerning possible dental side effects caused by the MAA. However, if lifelong treatment of OSA is considered, these follow-up examinations are of utmost importance. This article presents 2 cases with unexpected dental side effects and occlusal alterations caused by MAA therapy.